NEURO LEC 7: BRAINSTEM Flashcards
What are the 3 longitudinal divisions of the brainstem?
Basilar - front (boobs)
Tegmentum - middle (but think posterior brainstem, TUSH in the back)
Tectum - back
The tectum is only found in the….
Midbrain
What does the tectum consist of?
Superior + inferior colliculus and pretectum
visual and auditory processing and reflexive eye movements
What is inside of the tegmentum
sensory nuclei and ascending sensory tracts (its in the back!)
Reticular Formation
CN V nuclei
medial longitudinal fasciculus (coordinates head and eye mvmt)
What is inside of the basilar division?
descending axons from cerebral cortex, corticospinal, corticobrainstem, corticopontine, and corticoreticular tracts
Motor nuclei from substantia nigra, pons, and inferior olive
Basically a bunch of motor stuff (all tracts that start with cortico-)
What is in the basis pedunculi?
Cerebral peduncles (motor tracts from cortex)
substantia niagra nucleus
What’s in the MIDBRAIN tegmentum?
ascending sensory tracts
superior cerebellar peduncle (sensory from midbrain to cerebellum)
red nucleus
medial longitudinal fasiculus
periaqueductal gray
What does the superior colliculus do?
motor and sensory info to orient head and eyes
What does the inferior colliculus do?
relays info from cochlear nerve to superior colliculus and thalamus
auditory processing
The pretectal area of the midbrain does what?
mediates eye reflexes
What kind of matter is the red nucleus made out of?
Gray matter
What cranial nerve nuclei are found in the midbrain tegmentum
3 and 4
Pons forms the anterior wall of what?
fourth ventricle
cerebellum is posterior wall
What 2 tracts synapse in the pons? Most of the tracts do not
corticopontine tract- Synapse on pontine nuclei -> pontocerebellar fibers -> middle cerebellar peduncle -> synapse in contralateral cerebellar hemisphere
corticobrainstem tract - synapses with trigeminal motor nucleus and facial nucleus
What kind of fibers are in the superior cerebellar peduncle?
need to check
What can you find in the basilar portion of the pons?
Descending tracts- corticospinal, corticobrainstem, corticopontine
Pontine nuclei
Pontocerebellar axons
What can be found in the tegmentum of the Pons?
Sensory Tracts
Reticular Formation
Autonomic pathways
CN 5,6,7,8 nuclei
What cranial nerve nuclei exits between the pyramid and inferior olive?
CN 12
Which cranial nerves exit in the lateral groove of the medulla, lateral to olive?
IX, X
What is the nucleus ambiguus for?
Motor output to swallowing/vocalization muscles
(Which would be CN 9, 10, and sometimes 12?)
BIG MOUTH
inferior olivary nuclei receive info from many cortical and SC motor areas and then project where?
what info are they sending?
contralateral cerebellum through olivocerebellar tract
motor learning, timing and control of ongoing movements
nuclei of CN __ at medullopontine junction
VIII
What is the only tract that enters the medulla from the cerebellum
(The rest enter medulla -> _____ cerebellar peduncle -> cerebellum)
Cerebellovestibular tract
(starts with cerebellar because its coming from there!)
INFERIOR cerebellar peduncles (medulla is lowest, so inferior peduncles)
Solitary nucleus - CN’s and fxn
7, 9, 10
taste, oral sensations and visceral sensations (vagus/X)
Solitary confinement - inside sensations and bad food
The DCML crosses in the inferior medulla ________ to the crossing of the corticospinal tract
Posterior
sensory in the back!
motor in front
what vessels supply the midbrain?
PCA, branches of basilar artery
SCA not on slide
what supplies the medulla with blood?
PICA, anterior spinal artery
vertebral and posterior spinal arteries on pic but not slide so don’t stress
What supplies the pons with blood?
AICA, basilar
What are the 4 brain stem tracts?
Rubrospinal Vestibulospinal Reticulospinal Tectospinal
RVRT
What are the general brain stem functions
Modulates consciousness - reticular formation
Regulates vital signs
Conveys signal from cortex to spinal cord
*What are the 4 cardinal signs of brain stem dysfunction? 4 Ds
Dysphagia, Dysarthria, diplopia, dysmetria
dysarthria - “articulate” difficulty speaking
diplopia - double p for double vision
what specific part of the brainstem regulates vitals?
Damage to brain stem could cause….
medullary and pontine centers
Heart to stop beating
BP to fluctuate
Breathing to stop
Disorders of conciousness are due to damage of_______
Reticular activating formation/ reticular formation
People in vegetative or minimally concious states have loss of tissue in subcoritcal/thalamic/brainstem regions
brainstem lesions will cause ____ signs
vs
single cranial nerve or cranial nuclei lesion will cause ____ signs
contra or ipsi - depends on where tracts cross and where the damage was
ipsilateral
lesions of ______ and _____ tracts in the brainstem usually cause contralateral signs because these tracts cross the midline in the inferior medulla
lateral corticospinal
dorsal column tracts
Anteriormedial midbrain syndrome (webers) is caused by….
Blockage of PCA or Basilar artery
What are the primary structures affected by Anteromedial midbrain syndrome (webers)
Corticospinal tract- contralateral motor paralysis
Occulomotor nerve nucleus- Ipsilateral loss of eye movements. Paralysis of eyelid, dilated pupil (PTOSIS)
Red Nucleus- loss of motor coordination, ataxia, CONTRALATERAL, inappropriate laughing and crying. Lability
What does CN3 palsy look like?
Eye deviated down and out
Lateral inferior pontine syndrome is due to occlusion of the….
Anterior inferior cerebellar artery
What are the clinical manifestations of lateral inferior pontine syndrome
Think: What CN nuclei are there? Ipsi vs Contra effects? What tracts affected?
CN V - ipsi facial pain & temp sensation loss
CN VII - ipsi facial weakness and expressions
salivatory nucleus (CN VII, IX) - decr tears and salivation
CN VIII - hearing loss, dysequilibrium, nausea
spinothalamic tract - contra pain and temp sensation loss for body
sympathetic nerve fibers - ipsi horners syndrome
Damage to what nerve causes Bell’s palsy
How will Bell’s palsy differ from a facial weakness after stroke
Facial nerve - ipsi, whole half of face
Stroke is usually only lower facial weakness on CONTRA side
(Upperface muscle preserved due to dual innervation of the upper face)
What is Horner’s syndrome?
Miosis- pupil constricted
Ptosis- drooping eye lid
Anhidrosis- drying of skin in the area (look at the word)
Damage to sympathetic nerves
Locked in syndrome is due to damage of the….
Basiliar artery impacting the ventral pons bilaterally
What are the primary structures involved in locked in syndrome-
B corticospinal tracts- paralysis below the head
B corticobulbar tracts- paralysis of facial muscles
B abducens tracts- unable to move eyes to side
Note: most of the time cranial nerve 3 is preserved but sometimes its impacted
What are spared in locked-in syndrome?
Reticular activating formation/ reticular formation
Vertical gaze centers are spared.
Middle medullary syndrome is caused by a blockage in the ….
Anterior spinal artery
What is the 2nd most common place to have a stroke in the brainstem?
AICA
What are the primary structures affected by MEDIAL medullary syndrome
what’s medial in the medulla? what CN? tracts?
hypoglossal nerve- ipsilateral tongue protrusion
DCML- contralateral loss of DCML senses (light touch, proprioception, vibration)
Lateral corticospinal- contralateral hemiparesis (weakness or paralysis to side of body)
Remember the hypoglossal nerve comes off of the medial medulla!
What is the most common brainstem stroke, and what artery causes it?
Lateral medullary syndrome (wallenberg)
Due to blockage of PICA
What structures are affected due to Wallenberg syndrome (lateral medullary syndrome)
Vagus nerve/Solitary nucleus- elevated HR
Vestibular nucleus- balance
Vagus nerve nucleus- altered vitals
Trigeminal Nerve
Inferior cerebellar peduncle - ataxia/coordination ipsilateral
Salivatory nucleus - unable to salivate or make tears
Spinothalamic tract- contralateral
Descending sympathetic- ipsilateral Horner syndrome
Nucleus ambiguus (9 10) and 12 cranial nerve. Tongue/ larynx/pharynx affected. Lack of gag reflex, speech issues
The reticular formation is in the _______ of the pons
tegmentum
